This application relates to systems, devices and techniques in connection with optical polarization.
Optical polarization is an important parameter of an optical signal in various optical systems. For example, in fiber optic communication systems, polarization-dependent effects in fibers and other devices, such as polarization-dependent loss (PDL) and polarization-mode dispersion (PMD), can have significant impacts on performance and proper operations of optical devices or systems. Hence, it may be desirable to measure, monitor or control the state of the polarization (SOP) of an optical signal in these and other systems.
Two orthogonal polarization states of an optical signal can experience different delays in an optical material and this difference is known as the differential-group-delay (DGD) of the optical material. DGD modules have various applications, especially the emulation or compensation of polarization mode dispersion (PMD). Various DGD modules are available and some of these DGD modules suffer one or more technical limitations, including (i) modification of the polarization properties of the input light for the worst-case monitoring; (ii) introduction of higher-order PMD when folded optical paths are used; (iii) being relatively bulky in size.